J-FG₃立式金属线胀系数实验器

  仪器利用弹性梁的弯曲，测定金属材料的杨氏模量。仪器由在基座上相对移动的两个平行刀口及搁在上面的弹性钢梁组成，钢梁中段套着具有刀口向下的矩形杠，它的下端，可悬挂砝码，当悬重P作用于钢梁而使梁弯曲时，其弛重量可通过上面安排的砝码显示表准确读取。从而计算出钢梁材料的杨氏模量

配合光杠可精确测量微小的位变，如长度、厚度及角度的变化等。                         

  QGD-400气动定值器QGD-300.J-FG3实验器技术参数：                                           （1）放大倍率：30^x                          

（2）物镜孔径：42mm                      

（3）视距乘常数：100                   

（4）视力场角：1°26’                   

（5）视距：1000mm    （6）调焦方式：内调焦

Structure and basic properties:

       QGD-400气动定值器QGD-300.J-FG3实验器本仪器为一大型音叉，由整块的钢材切削而成。在两叉枝的顶端，装置记录笔尖一对，以供记录波纹之用。叉柄固着于木质底板上的Ω型底坐上，在两叉枝间距叉顶约三分之一处，装置一电磁铁，在左侧叉枝的外侧配备断续接触器，接通电流后，配合音叉的振动，形成励磁线圈断续通电，致使电磁铁产生间断吸力，驱使音叉作长期的振动。本音叉频率约为100周/秒，每具音叉的实际频率数均用硬印标出。标出的频率数据就是是音叉顶部装有一对记录笔尖的频率，如将此等附件连同螺丝全部卸去，则频率约增加4分之3周。由于音叉叉枝质量较大，故在实验中如弦振动驻波试验等，负荷稍有变动时，对频率的影响不大。

This instrument is a large tuning fork made from the cutting of one-piece steel material. A pair of recording pen-points is mounted at the top of two branches for the purpose of recording ripples. Fork handle is fixed on the Ω type seat of wooden bottom plate, one electromagnet is arranged between two fork branches and about one third away from the fork top, and an intermittent contactor is mounted at the outside of left-side fork branch. After the power supply is switched on, it is possible to form excitation coil, provide intermittent electricity, cause the electromagnet to produce intermittent suction, and drive the tuning form to produce long-term vibration. The frequency of tuning fork is 100 cycle per second, and the actual frequency number of each of tuning fork is marked with embossing seal. The marked frequency data equals to the frequency of a pair of recording pen points mounted at the top of tuning fork, and the frequency may increase 3/4 cycle, provided that these accessories and other screws are completely dismantled. Due to the larger mass of tuning form branch, slight changes in load may not have significant impact on frequency in such experiment as string vibration standing wave test.

QGD-400气动定值器QGD-300.J-FG3实验器使用方法：